New amp needed for Superlux Hd668B?

Having recently moved into the world of high quality sound, I could use some clarification on some few details. I want to make sure that I am using the 668B's at or near their true potential with the Fiio E5 amp that I am using.

So amps – there use... From what I understand it is that high quality headphones can't get enough charge from most of the devices people use nowadays, so the amp comes into play to fix that. Headphones high in number require amps to provide wanted volume levels while lower numbers need amps to give wanted sound quality. The number for energy output is like the headphones' number divided by eight or something if I remember correctly...

So along with the HD668B's I got the Fiio E5 headphone amp, understanding that with the 668B's I would need under 7 (if I remember correctly) output, and the Fiio E5 headphones give under 1. Since the amps can drive the headphones to volumes much louder than I could ever bear to listen at, I assume that the headphones are getting the energy that they need, but due to this being my first time I am not sure if this is relevant in the matter.

I've noticed that there are much more expensive headphone amplifiers out there, portable and non-portable (I want portable), and I've taken into wondering what causes the difference in cost? How are they upgraded? I've read reviews that say these amps give better sound quality than the Fiio E5 – does that sound quality apply to all headphones? Or – what exactly do they mean by better sound quality? I've seen the word 'stage' used but don't understand what that means. Does this mean amps do more than provide energy to headphones?

If I were to get a different amp to replace these, I would hope to keep the price around forty dollars at most. I guess in terms of price, is the Fiio E5, at 30$, the best for what I am willing to pay?

If someone could help me out on these questions, or at least some of them, that would be great :).

Most often I use the ipod/mp3 built into my phone, and I use my computer as well.

Well now that you got me thinking about it, when I first read that the sound quality depends on the headphones, the amp, and the source, I just assumed the source refers to the quality of the recording being listened from. So... I need a "Dac?"

How I interpret this is I need a DAC for the computer but not for the phone. How correct is this? The article makes it seem like I should get the E10 since I do computer listening. Also, the article makes me wonder if it is worth keeping the E5's because it says amps may not be needed unless if the headphones are not giving enough volume. I'm not sure of the accuracy of the article because this conflicts with my previous idea that high quality headphones that are high in numbers require an amp for volume quantity while low numbers need it for sound quality.

Most often I use the iPod/mp3 built into my phone, and I use my computer as well.

Well now that you got me thinking about it, when I first read that the sound quality depends on the headphones, the amp, and the source, I just assumed the source refers to the quality of the recording being listened from. So... I need a "Dac?"

How I interpret this is I need a DAC for the computer but not for the phone. How correct is this? The article makes it seem like I should get the E10 since I do computer listening. Also, the article makes me wonder if it is worth keeping the E5's because it says amps may not be needed unless if the headphones are not giving enough volume. I'm not sure of the accuracy of the article because this conflicts with my previous idea that high quality headphones that are high in numbers require an amp for volume quantity while low numbers need it for sound quality.

Both your computer's motherboard and the iPod come with a built in DAC chip.

Chances are the DAC chip in the iPod is a fair bit better then the one in the motherboard.

For you computer, just get the Asus Xonar DG sound card, $30 and there is a $10 mail in rebate this month.

You can not cheaply add an external DAC to the iPod.

Best thing to do with the iPod is to get something like the Fiio E11 portable headphone amplifier, $63, along with a FiiO L cable, $10.

But for that kind of cash you could get headphones like the JVC HA-S680 folding on-ear headphones, $80, for use with the iPod.